Sprockets that are used in timing belt power transmission systems must have very tight tolerances to work properly. As diameters of sprockets increase, not only does it become more difficult to hold the tight tolerances (geometrical effect), but the expansion and contraction of the metallic material of the sprocket also adversely affects tolerances. In some applications such as large modern wind power generators, the diameter and the width of a power transmission sprocket has to be over 1.5 meters and the temperature fluctuations in the housing on the top of the wind tower could be in the range of over 100 degrees Celsius. Subsequently, using a belt drive system becomes very challenging if the sprockets tolerances are too variable.
Representative of the art is U.S. Pat. No. 5,074,406 which discloses a sprocket arrangement which provides increased contact surface area for driving conveyor belts is disclosed. The sprocket is particularly suitable for abrasive applications and/or use with modular plastic belts. The sprocket is formed by stacking and aligning a multiplicity of thin substantially disk shaped sprocket lamina together and then joining the stacked and aligned lamina by simply bolting or welding. Each of the sprocket lamina includes a central aperture for fitting onto a drive shaft. Teeth or other driving surfaces are also formed around the perimeter of each of the lamina. The lamina may be stacked in contact with each other, or for some applications may use spaces to separate selected ones of the stacked lamina so as to cooperate with the structure of the belt being driven.
What is needed is a method of forming a sprocket by assembling components on a mandrel to make a build and then joining the build to a rigid core. The present invention meets this need.